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8/9/2019 Cvd Introduction
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8/9/2019 Cvd Introduction
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Introduction to Chemical Vapor Deposition
A) Chemical Vapor Deposition
CVD TypesCVD Uses
CVD Process
General CVD Reactor Concept
General CVD Process Advantages
General CVD Process Applications
B) Dealing ith !ngineering "cience o# CVD Reactions
Transport Processes
$aminar %lo Boundary $ayer Concept
&ther "usceptor to %lo A'is &ptions
Thermodynamics
Reaction (inetics
C) &perational &vervie
Polycrystaline "ilicon
"ilicon Dio'ide
itride %ilms
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LPCVD APCVD
PECVD
Chemical Vapor Deposition
Current &ptions
Atmospheric Pressure CVD
Plasma !nhanced CVD
$o Pressure CVD
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CVD
"ilicon itride
"ilicon dio'ide Polycrystalline"ilicon
!pita'ial $ayersCustomi*ed "ur#aces
Insulator Conductors
Barriers
Chemical Vapor Deposition
CVD Applications
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Arrival Flow
Rate
"u+strate
Input Flow Rate
r , Groth Rate o# %ilmg
rg
"ur#ace Reaction Rate
G r o t h R a t e
% i l m
Chemical Vapor Deposition
CVD Process
"ur#ace Reaction
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CVD Reactor Concept
Reaction Chamber
SusceptorControlled Thermal Environment
Controlled Pressure Environment
Film Surface
Hydrogen Carrier Gas
With additional film significant containing gas components
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General CVD Process Advantages
Excellent Step CoverageLarge hro!ghp!t "#$$ A%min film gro&th'Lo& emperat!re Processing "()$ to #$$$ C'
Applica*le to any Vapori+ation So!rce echnology"Laser CVD for direct Writing'
General CVD Process Applications
Epitaxial ,ilmsEnhance performance of Discreet and -ntegrated .ipolar Devices
Allo& ,a*rication of /A01s and C02S in .!l3 S!*strate
Dielectrics-ns!lation *et&een Cond!cting LayersDiff!sion and -on -mplant 0as3sCapping Dopant ,ilmsExtracting -mp!ritiesPassivation to Protect Str!ct!res from
-mp!rities0oist!reScratches
Polysilicon Cond!ctorsGate ElectrodesCond!ctors for 0!ltilevel 0etali+ations
Contacts for Shallo& 4!nction Devices
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.' Dealing &ith Engineering Science of CVD /eactions
ransport Processes
hermodynamics
/eaction 5inetics
ransport Processes
!r*!lent ,lo& 6o7 to 0any Particles8
0olec!lar ,lo& 6o7 to Lo& a hro!ghp!t
Laminar ,lo& " 2nly 2ne Left7 0a3e Do'
Set Conditions ,or Laminar ,lo& " Lo& /eynolds 6!m*er Val!e'
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R = D V !
/eynolds 6!m*er
Linear Velocity
!*e Diameter
9 "
Gas Density
Gas Viscosity
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Laminar ,lo& Conditions
Diameter and velocity in tens of cm and cm%s &ill give
/eynolds n!m*ers in laminar flo& regime
R = #$%& ' #()
*rowth D +R! #+ T !
#$&%
T+ , ! -! P!.oundar, /a,er
Thic0ness
Rea1ent Partial Pressure
Rea1ent2s *as Phase Coe33icient
o3 Thermal Di33usion
($44
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S!sceptor
Input Reactant *as Flow
.o!ndary layer develops along s!sceptor flo& axis
X1
X2
X3
X4
*raphic E'a11erated 3or Visual E33ect
Velocity Gradient Profiles at Discrete Points along ,lo& Axis
1 2 3X
4X X X
: n d e r d e
v e l o p e d
f l o & p a t t
e r n a t t h i s
p o s i t i o n a l o n g
s ! s c e p t o r
D i s t a n c e A * o v e S ! s c e p t o r
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rends in GradientsVelocity Val!es
-ncrease Along S!sceptor-ncrease A*ove S!sceptor
emperat!re Val!es-ncrease Along S!sceptorDecrease A*ove S!sceptor
/eactant Concentration Val!e
Decrease Along S!sceptor-ncrease A*ove S!sceptor
Velocity Gradient Profiles at Discrete Points along ,lo& Axis
1 2 3X
4X X X
: n d e r d e v e l o p e d
f l o & p a t t
e r n a t t h i s
p o s i t i o n a l o n g
s ! s c e p t o r
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2ther S!sceptor to ,lo& Axis 2ptions
Design ,actors -ncl!de ,lo& Direction and Wafer Angle
A' -np!t gas flo&
.' -np!t gas flo&
C' -np!t gas flo&
D' -np!t gas flo&
E' -np!t gas flo&
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hermodynamics
CVD Phase Diagram
Give range of inp!t conditions for CVD that co!ld prod!ce specificcondensed phases8
Presented as ,!nction of emperat!re or Press!re vs 0ole ,raction
.
.oron codeposit only in High
.oron 0ole ,ractions in inp!t
stream
.oron codeposition favored at
higher press!res81200
oC
1000o
C
1400
o
C
/eactant Gas 0ole ,raction
.%"i ; .'
$8$# Atm #8$ Atm
$8<
i. = Phase
H%HCl > $8?)
Use Graphic for Educational Value Only 7 th
Conference on CVD 1979
K.E. Spear
Electrochemical Society Vol 79
i.
=@
.Phase
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.Cl %CH ( > (
Use Graphic for Educational Value Only
J. Electrochem. Soc. 123 ,136, 1976
Bernard Ducarror
#$ B(
#$ B
#$ B=
#$ B#
#$ B$
#$ B(
#$ B
#$ B=
#$ B#
Partial Pressure 3or 5ethane
.6C 7 C
.6C
.6C 7 .
.
CarbonVapor
#&(( ( C
#$( Atm
.oronBCar*on CVD Phase Diagrams
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1 0 0 0 o C
9 0 0 o C
1 1 0 0 o C
I n p u t e a c t a n t ! a " # o l e F r a c t i o n
S i % " S i ; V '
$ 8 <H % H C l > $ 8 ? )
U s e G r a p h i c f o r E d u c a t i o n a l V a l u e O n l y
7 t h C o n f e r e n c e o n C V D 1 9 7 9
K . E . S p e a r
E l e c t r o c h e m i c a l S o c i e t y V o l 7 9
1 2 0 0 o C
VCl8
VCl8 7 V)Si4
V)Si4
P > $8=) atm
Vanadi!mBSiliconBHydrogenBChloride CVD Phase Diagrams
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Vanadi!mBSiliconBHydrogenBChloride CVD Phase DiagramCom po" ition ratio" for input $a"e" of VCl 4 %SiC l4 % &2 are not e'uili(rium )alue"
ransport Processes vs hermo dynamics
*a"+, # a+ e a V- S i3 film.
roc e/ ure , F rom C V h a"e ia$ ra m fo r a 9 00 oC / epo"ition an input $a" mo le
fraction of 0.20 can (e u "e/.
ro( lem , " V- S i3 form " on "urface actual rea$ent $a" S i mo le fraction co n"um e/
at "urface i" hi$her 0.37- than the input reactant $a" ratio "upplie/
0.20. *hu" Si at "urface i" /ep lete/ more Vana/ium i" a)a ila( le at the
"urface a n/ ac tual e'u ili(rium "hift" to pro/uc tion of V 3Si.
roce/ure, &ol/ temperature con"tant (ut "hif t the input $a" mole fract ion to 0.-.
ro( lem , " V- S i3 form " on "urface actual rea$ent )ana/ ium $a" m ole fraction
con"um e/ 0.52- i" hi$her than the input $a" mo le fraction for )ana/ ium .
*hu" Vana/ium at "urface i" /eplete/ more Silicon i" a)aila(le at the
"urface a n/ actual e'uili(rium "h ift" to pro/uction of VSi 2.
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/eaction 5inetics
Use Graphic for Educational Value Only
12!, 79" #1979$
Be%mann ,J. Electrochem. Soc.
#+T ' #( + 9!
-.0 5.0 7.0 6.0 9.0
1.0
10.0
Titanium Diboron Deposition Arrhenius Plot
P = ($8&4 Atm$
Input 3low Rate = 6&8 cc +min
.+. 7 Ti! = ($&&
Cl+Cl 7 :! = ($44
Input *ases
TiCl6
.Cl4
:8
Reaction Temperatures 8((( 9 to #((( 9!
;#
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Use Graphic for Educational Value Only
Arrhenius Rate Pro3iles
#+T
1.0
10.0
af
/ower Sur3ace Temperatures:i1her Sur3ace Reaction Rates
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Use Graphic for Educational Value Only
Partial Pressure Reactant *as
1.0
10.0
Arrhenius Isotherms
a
fSur3ace Reaction /imitin1 *rowth Rate
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# + T
.est Fit 5odel .ehavior based
<perational /ine 3or Deposition at :i1her Pressure
r1#
<n ) Calibration Runs
#+ T 8
r18
Desired *rowthRate
ew <peratin1Temperature
#+ T#
Current
<peratin1 Temperature
Current
*rowth Rate
ln (r g2
/ r g1
) (q act
/k ) (T 2 T
1 / T
2 T
1)
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Silicon dioxide
Lo& emperat!reLoose adhering deposits on side &alls of reactor8 " Particles that cancontaminate the film8
At high silane press!res allo&s for gas phase reactions8 " Promotesparticle contamination and ha+y films'
,air step coverage
Lo& film density " =8 $ g%cm '
Deposition rate complex f!nction of 2xygen concentration
Easy chemical reaction8 " Lo& activation energy7 $8( ev "#$ 3cal%mole' '
,ilm depends on gas phase transport of material to s!rface
Lo& temperat!re allo&s prod!ction of films that &ill serve as
ins!lation *et&een al!min!m levels in device8
Si
:
::
:
Si72
<'idation$
6(( ; 6)( C72
Films Contain :,dro1en as
Silanol Si<:!:,dride Si:!
<r @ater
Amorphous Structure o3 Si<6 Tetrahedra
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Si
:
:: :
Si 2
<
&)( to %)( C
Si
<
C
C
:
:
:
:< <
C
:
:
C
:
:
C&2C&3
C&2C&3
Silane Tetraetho',silane
TE<S
Si 2
&)( to %)( C/PCVD!
4( PA to 8)( PA
#(( to #((( std$ cc + min
0edi!m emperat!re
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S i
C l
:C l :
S i 7 2
= 8 < $
A ) ( t o ? ( ( C
D i c h l o r o s i l a n e
/PCVD
itrous <'ide
High emperat!re
6onlinear press!re dependence that is f!nction of &afer position8
Small amo!nts of Chlorine in films that tends to ca!se crac3ing in a poly layer'
/eagent depletion pro*lems
Phosphor!s doping is diffic!lt8 " he phosphor!s oxides are volatile at highdeposition temperat!res8'
Excellent :niformity
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Except for epi and parallel plate processes both sides of wafer are coated.
Equipment
Furnace with or without vacuum capability Plasma hamber
CVD is Cr!cial to ,a*rication of -Cs7 Especially 02S,ES
!"he #ottom $ine%
Pad &ilicon 'ioxide
First (onolayer of &ilicon )itride
&i
l
l
)
* *
Precursor
NH Si Cl
* l
*
l
l l
*
*
)
* * *
&i
l
l *
* &i
l
l *
*